The investigators propose to develop robust criterion driven algorithms to compare and minimize differences between spectral shape models and the actual data. This allows the use of the full information in the spectral data to extract linewidth or other pertinent spectral parameters which are sensitive to the physiologic environment. Oxygen broadens the individual spin packet, homogeneous, or Lorentzian component of the spectral line with trivial effect on the inhomogeneous components of the spectrum. Models of distortion of the spectra from dispersion and accompanying absorption in lossy samples and diffusion will be tested to determine the depth distribution sensitivity of the spectra to be obtained.